Method for producing plasticcoated knitting needles



W. C- BATES Nov. 16, 1948.

METHOD FOR PRODUCING PLASTIC-COATED KNITTING NEEDLES 2 Sheets-Sheetl Filed Feb. 18,1947

Nov. 16 1948. w. c. BATES METHOD FOR PRODUCING PLASTIC-COATED KNITTING NEEDLES Filed Feb. 18, 1947 2 Sheets-Sheet 2 l atented Nov. 16, 1948 UNITEDSTATES PATENT}. OFFICE METHOD FOR PRODUCING PLASTIC- COATED KNITTING NEEDLES Wells 0. Bates, Chester, Conn, assignor to C. J. Bates & Son; Chester, Conn, a partnership composed of Hamilton C. Bates, Sin, Wells 0. Bates, and Hamilton C. Bates,Jr.

Application February 18, 1947, Serial No. 729,259 4 Claims. (01. 18-59) The present invention relates to improvements in methods or processes for producing knitting needles and relates more particularly .to improvements in methods or processes for. p oducin plastic-coated kntting needles.

Heretofore, in efforts to provide knitting needles with plastic coatings of appreciable thickness. it has been proposed to repeatedly dip the knitting needle in a solution or dispersion of the desired plastic material. This method requires long pauses between the application of each relativelythin coating and is thus slow and expensive, as well as being otherwiseunsatisfactory.

One of the main objects of the present invention is to provide a simple, reliable and efiective method whereby knitting needles may be rapidly provided with a relatively-thick coating of plastic materials.

Another object of the present invention is to provide a superior-method whereby knitting needles may be provided with coatings of substantial thicknesses at a low cost for manufacture.

With the above and other objects in view, as will appear to those skilled in the art from the present disclosure, this invention includes all features in the said disclosure which are novel over the prior art.

In the accompanying drawings, in which certain modes of carrying out the present invention are shown for illustrative purposes:

Fig. 1 is a perspective view of a pair of complemental mold-members shown as engaged in faces to-face relationship;

Fi 2 is a perspective view of the upper mold- Inember, viewing the same mainly from its underside; i

Fig. 3 is a similar view of the lower'mold-memher but viewing the same mainly from its upper side;

Fig. 4 is a perspective View of a core-member suitable for being coated in accordance withthe present invention, to provide a plastic-coated knitting needle;

Fig. 5 is a broken longitudinal sectional view taken on the line 55 of Fig. 1, but on a larger scale and showing-a core-member in its initial or centered position and the plastic material as having been flowed therearound; i

Fig. 6 is a transverse sectional view taken on the line B--5 of Fig. 5; V

Fig. 7 is a horizontal sectional view taken on the line 1-1 of Fig. 5;

Fig. S-is a broken enlarged-scale sectional view equivalent to a section taken on the line 8- 8 of Fig. '7, but including also the upper mold-member;

Fig. 9 is a view similar to Fig. 7 but showing the core-members retired to permit the completlon of the tips thereon;

Fig. 10 is a broken enlarged-scale sectional view equivaicnt to a section taken on the line l0lfi ofFigl 9, but including the upper mold-member also; p

Fig. 11 is a broken sectional view similar to Fig. 8 but showing a core having a pointed end in placeinthe die-cavity;

Fig. 12 is. a view similar to Fig. 10, but showing the eifect of theslight withdrawal of the pointed core-member of Fig. 11 to permit the full formation offa tip-portion thereon;

Fig. 13 is a perspective view of a coated knitting needle after. the. severance of the projecting end] of its core-member and prior to'the application of a capthereto; and

. Figl i is a perspective view of a completed knit ting needle.

In .the accompanying drawings are illustrated two complemental mold-members suitable for use in carrying out the method of the present invention and which may be respectively designated as an upper mold-member Hi and a lower moldmember I l. The said complemental mold-members land II are adapted to be mounted in any suitable injection-molding machine, which latter does not require any description or illustration herein.

- In the instance illustrated in the accompanying drawings,. the upper mold-member I0 is provided atldiagonallywpposite locations with downwardly-extending guide-pins l2 and I3 which are respectively adapted to slide with a close sliding fit in passages l4 and 15 formed respectively at diagonally-opposite locations in the lower moldmember I l.

The upper mold-member H3 is formed in its un- The saidcavities iii are respectively adapted to register with and complement a similar series of v cavities l1 formed in the upper face of the lower mold member H. Each of the cavities l1 just referred to is of semicircular form in cross section and when registered with a similar cavity l-6 of the upper. mold-member 10, provides a complete cavity of circular form in cross section.

' At one end, each of the cavities l6 of the upper mold-member l 0 is connected to the adjacent end of the said mold-member by a seat-portion. l8 which communicates with the adjacent edge of the moldmember H1. The seat-portions l8 are each of semicircular form in cross section and are of a lesser radius than the radius of the main portion of the particular cavity IS with which they connect.

Each of the seat-portions I8 of the upper moldmember Ill is adapted to register with and complement one of three similar seat-portions I9 formed in the lower mold-member adjacent one end thereof. When the upper mold-member I8 and the lower mold-member II are engaged in face-to-face relationship, each seat-portion l8 registers with one of the seat-portions I9 to provide a cylindrical passage substantially corresponding in diameter to the diameter of a. rodlike core-member 20 of the character shown in Fig. l, or a core-member 32 shown in Figs. 11 and 12.

At its end remote from the seat-portions I8, each of the cavities It in the upper mold-member I is formed with a tapered tip-forming portion 2| which is adapted to register with and to complement a similar tip-forming portion 22, one of which latter is formed at the adjacent end of each of the cavities I! in the lower mold-member Leading from each of the cavities I! in the lower mold-member II is one of three similar channel-like gates 23 each of which leads at its opposite end from a channel-like runner 24 which, like the said gates 23, is formed in the upper surface of the lower mold-member I l, as is especially well shown in Figs. '7 and 9. The runner 24 leads from a flaring sprue-portion 25 formed in the edge of the lower mold-member The sprueportion 25 just referred to is complemented by a sprue-portion 26 formed in the similar edge of the upper mold-member I 8.

Preferably, the two sprue-portions 25 and 26 above referred to are cylindrically contoured and together provide a substantially-hemispherical socket adapted to receive the similarly shaped end of a nozzle Zi forming a usual feature of any suitable injection-molding machine.

In utilizing the mold-members I0 and I l and the blunt-ended core-members 20 as shown in Figs. 4 to inclusive, the two mold-members I0 and I may be first brought into face-to-face engagement following which three core-members 28 may be respectively inserted through the passages afforded by the seat-portions l8 and I9 until each of the said core-portions seats firmly against and is centered by a complemental pair of the tapered tip-forming portions 2| and 22, in the manner shown in Figs. 5, '7 and 8.

The core-members project outwardly beyond the respective ends of the mold-members I0 and II at which the seat-portions l8 and I9 are located and may there be supported in any suitable manner so as to maintain their opposite ends in engagement with the sloping portions 2| and 22 with any desired degree of firmness. The fit of the respective core-members 20 in the complemental seat-portions l8 and I9 through which they extend is reasonably snug but preferably the fit is such that air entrapped in the cavities may escape past the said seat-portions, to thus provide the required venting.

While the ends of the respective core-members 20 are firmly seated against their adjacent sloping tip-forming portions 2| and 22 and while the mold-members are hot, any suitable hot and fluid plastic material may be injected into the sprueportions and 25 from the nozzle 21 to flow through the runner 24 and thence through the respective gates 23 into each of the plurality of mating cavities I6 and I1 to completely fill the said cavities, with the exception of the point-portions thereof, substantially in the manner indicated in Figs. 5, 7 and 8. Thus, each core-member 20 will be laterally enveloped and provided with a plastic coating 28.

As shown in Figs. 5, 7 and 8, some of the plastic material (preferably a thermoplastic) may leak past the end of the core-members 20 which are seated against the tip-forming portions 2| and 22, though if desired, this may be prevented by very tightly seating the said ends of the coremembers against the said portions 2| and 22.

Immediately following the initial injection of plastic material in the manner above described, the core-members 20 are moved axially into the positions in which they are shown in Figs. 9 and 10, While the pressure of the plastic material from Q the nozzle is still being exerted. Under these conditions, the plastic material will resume flow and will fill out the tip-forming portions 2| and 22' of each of the cavities l6 and IT, to thus provide each of the said core-members with a. full tapering point-portion or tip 29 integral with the coating 28, as is clearly shown in Figs. 9 and 10.

The mold-members I6 and I may now be separated (after the nozzle 27 has been retired) and the unit comprising the group of core-members, their coatings, tips and the attached portions of plastic materials formed in the gates 23, runner 24 and sprue-portions 25 and 26, may be jointly removed.

After removal of the multi-part unit from the mold-members in the manner above described, each coated core-member may be severed from its respective gate and may have the portion of the core-member 28 which projects beyond the end of the plastic coating 28, severed in the manner indicated in Fig. 13, to thus produce what may be regarded as a completed knitting needle 30, as is shown in Fig. 13.

It is preferable, though not necessary, to then apply a suitable cap such as 3| over the end of the knitting needle 38 opposite its tip 29, in the manner illustrated in Fig. 14. The cap 3|, or its equivalent, may be retained in place by crimping, cement or by heating the plastic coating 28 to cause the adherence thereto of the said cap.

By means of the procedure above outlined, the core-members 28 are accurately centered during the formation of their respective coatings 28 and are then provided with suitable tips such as 29 by the mere action of withdrawing the said cores slightly, under conditions wherein the previouslyinjected coatings 28 are sufficiently firm to serve to hold the said cores from losing their central positions within the said coatings.

Instead of employing a blunt-ended core-member like 28, a core-member 32 may be employed which is provided with a tapered tip 33 prior to being coated, as is shown in Figs. 11 and 12.

A plurality of core-members 32 may be installed in the previously described cavities of the moldmembers I8 and II so that the tip 33 of a given core-member 32 firmly fits against the adjacent complemental tip-forming portions 2| and 22 of the individual cavities, in the manner illustrated in Fig. 11.

In the manner previously described in connection with the description of the formation of the knitting needle 30, a suitable plastic material may be injected around. the said core-members to provide coatings 34, after which the said coremembers may be slightly withdrawn into the position illustrated in Fig. 12 and the injection of the plastic continued to provide a plastic point-portion or tip 35 for each of the said cores. The tip 35, unlike the tip 29, will itself be reinforced by the tip 33 of the core-member 32.

The core-members 2D and 32, or their equivalents, may be made of any suitable material providing the desired degree of rigidity such, for instance, as aluminum, steel, brass, hard wood, etc.

The plastic materials referred to may also assume a wide variety of forms such for instance, as cellulose-acetate, ethyl-cellulose, styrene resins, nylon, rubber, phenolic-base compounds, etc.

The invention may be carried out in other specific ways than those herein set forth without departing from the spirit and essential characteristics of the invention, and the present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive, and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

I claim:

1. The method for producing plastic-coated knitting needles which includes the steps of: movably supporting a rod-like core-member of relatively-small diameter in an elongated molding-cavity of relatively-large diameter throughout the major portion of its length and which cavity is formed at one end with a tapering tipforming portion; forcing an end of the said coremember into engagement with the tapering tipiorming portion of the said cavity to hold the portion of the core-member adjacent its said end' out of engagement with the walls of the cavity proper; injecting a plastic coating material around the said core-member while the same is thus centered; and subsequently slightly axially retiring the said core-member out of engagement with the tapering tip-forming portion of the said cavity before said coating material loses its plasticity and forcing the said coating material to fill the said tip-forming portion and thus provide the now-coated core with a unitary tapering tip of plastic material.

2. The method for producing plastic-coated knitting needles which includes the steps of: movably supporting a rod-like core-member of relatively-small diameter in an elongatedmoldingcavity of relatively-large diameter throughout the major portion of its length and which cavity is formed at one end with a tapering tip-forming portion; forcing an end of the said core-member into engagement with the tapering tip-forming portion of the said cavity to hold the portion of the core-member adjacent its said end out of engagement with the walls of the cavity proper; injecting a plastic coating material around the said core-member while the same is thus centered; and subsequently slightly axially retiring the said core-member out of engagement with the tapering tip-forming portion of the said cavity before said coating material loses its plasticity and while still maintainng the said plastic material under pressure to thus cause the said coating material to fill the said tip-forming portion and thus provide the now-coated core with an integral tapering tip of plastic material.

3. The method for producing plastic-coated knitting needles which includes the steps of: inovably supporting a pointed rod-like core-member of relatively-small diameter in an elongated molding-cavity of relatively-large diameter throughout the major portion of its length and which cavity is formed at one end with a tapering tip-forming portion; forcing the point of the said core-member into engagement with the tapering tip-forming portion of the said cavity to hold the portion of the core-member adjacent its said point out of engagement with the walls of the cavity proper; injecting a plastic coating material around the said core member while the same is thus centered; and subsequently slightly axially retiring the point of said core-member out of engagement with the tapering tip-forming portion of the said cavity before said coating material loses its plasticity and forcing the said coating material to fill the said tip-forming portion and thus provide the now-coated core with a unitary tapering tip of plastic material surrounding its said point.

4. The method for producing plastic-coated knitting needles which includes the steps of: movably supporting a pointed rod-like core-member of relatively-small diameter in an elongated molding-cavity of relatively-large diameter throughout the major portion of its length and which cavity is formed at one end with a tapering tip-forming portion; forcing the pointed end of the said core-member into engagement with the tapering tip-forming portion of the said cavity to hold the portion of the core-member adjacent its pointed end out of engagement with the walls of the cavity proper; injecting a plastic coating material around the said core-member while the same is thus centered; and subsequently slightly axially retiring the point of said core-member out of engagement wtih the tapering tip-forming portion of the said cavity before said coating material loses its plasticity and while still maintaining the said plastic material under pressure to thus cause the said coating material to fill the said tip-forming portion and thus provide the nowcoated core with an integral tapering tip of plastic material surrounding its said point.

WELLS C. BATES.

REFERENCES EITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 222,229 Beals et al. Dec. 2, 1879 760,191' Gaylord May 17, 1904 1,731,280 Warren Oct. 15, 1929 2,197,465 Brunetti Apr. 16, 1940 

